The Devoted One
Bhakta ('one who is devoted,' from bhaj, 'to share in, to be devoted to') is the term for a practitioner of bhakti — the loving, devoted relationship with Bhagavān. A bhakta's life is oriented around the love of Bhagavān: thinking of Him constantly, serving Him, praising His qualities, and seeking to draw closer through all available means.
Grades of Bhaktas
The Bhagavad Gītā (7.17–18) identifies four types who approach Bhagavān (ārthi, jijñāsu, arthārthī, jñānī) and counts the jñānī-bhakta — the wise devotee — as the most intimate to Bhagavān, 'for I am dear to the jñānī and the jñānī is dear to Me.' But the Bhāgavata Purāṇam expands this to celebrate all grades of sincere devotion.
Bhāgavata-śeṣatva
In the Śrī Vaiṣṇava tradition, one of the highest callings is not merely being Bhagavān's servant but being the servant of His servants — bhāgavata-śeṣatva (tadīya-śeṣatva). Serving other bhaktas, honoring them, and learning from their love is held to be as meritorious as direct service to Bhagavān.